1. Field of the Invention
This innovation relates to clock phase generation and in particular to variable clock phase generation over a wide range of frequencies.
2. Related Art
Numerous electronic and communication systems process received data signal or an internal data signal. As part of the processing of data, it is typical to lock or synchronize a local clock signal, or other type signal, to the data being processed. An important aspect to synchronizing to the data signal is locking local clock to the phase of the data signal. Because the frequency of the data signal may vary, or the system may be configured to operate as numerous different frequencies, it is important for a system to accurately adjust or lock to the phase of the data signal.
Numerous situations exist where locking a local clock is needed. For example, for data processing it may be necessary to lock a local clock to an incoming data signal, such as if the phase of the incoming data is not known. Some type of locking mechanism or system is needed to change or adjust the phase of the local clock to the data. Thus, the system must steer or modify the local clock phase to lock to the data.
In another example application, a system may be configured to monitor data to create an image of the data. The data may be part of a data stream or on chip. The data being sampled may have a phase which varies over time or may depend on the data itself. As a result, there is a need to adjust the phase to the local clock to insure accurate sampling timing and sampling frequency to create the image of the data. In such an embodiment, the phase may be swept to accurately sample the data and thus there is a need for an accurate and variable phase.
Prior systems and method would typically generate I & Q signals which are varied of modified by a ratio or percentage. Thus, by interpolating between I & Q signals, the phase can be swept such that the interpolation ratio determines the variable phase.
While this approach yields acceptable results for narrow frequency bands and lower application frequencies, it suffers from several drawbacks at higher frequencies and over wide frequency bands. For applications with over a broad range of frequencies, the prior art suffers from several drawbacks. For example, for applications which require operation at 28 GB/s data rates but also support data rates down to 2-3 Gb/s, the prior art is unable to accurately accommodate these frequency ranges. This a 10× range of data rates. For example the prior art phase blender circuitry, using ratio processing between the I & Q signals, becomes very complicated and accuracy suffers.
Thus, there is a need for a new, accurate, and reliable system and method to create a variable phase signal which may be applied over a wide range of frequencies and which operates at any data rate and is independent of data rate.